Recently, mini-discs (MD) (Tradename) using magneto-optical disc as recording medium, and adapted for compressing digital audio data to record compressed data thereonto and expanding such compressed data to reproduce therefrom data corresponding to original data have been being popularized. FIG. 29 shows a recording format in this mini-disc. As shown in this figure, one circumference of the mini-disc is divided into a plurality of sectors. One cluster is constituted by 36 sectors, and compressed digital audio data is recorded with this cluster being as unit.
In the case of mini-disc for recording, the leading three sectors of one cluster (=36 sectors) is caused to serve as a link sector, and the next one sector is caused to serve as sub data sector. To this sub data sector, sub data except for audio data is allocated. The link sector is caused to serve as an area for connecting clusters before and after, and audio data is recorded only in 32 sectors except for the link sector and the sub data sector.
On the other hand, in mini-disks dedicated to reproduction, data are continuously recorded (are not discretely recorded), and three sectors of the link area therefore become unnecessary. Accordingly, in this case, these three sectors are caused to also serve as sub data sector.
One sector consists of 2352 bytes (2332 bytes for data) , and 11 sound groups are allocated to two successive sectors. One sound group consists of 424 bytes, and audio data of the left channel and the right channel are allocated thereto by 512 samples (11.61 ms) in total. Recording of digital audio data is carried out with the sound group being as unit.
It is conceivable to use such mini-disc as, e.g., storage unit of computer. In this case, in order to carry out management of data of computer as file, since cluster (36 sectors) is too large a unit, it is preferable to have ability of recording data in a unit (e.g., sector unit) smaller than cluster. However, as described above, since it is prescribed by the standardization requirements that mini-disc must record data thereonto with one cluster being a unit, there is the problem that it is unable to record data in a unit smaller than one cluster (e.g., sector unit).
Further, for example, in the case of recording both data of computer and audio data onto a mini-disc, it is conceivable to partition in advance the area for recording data similarly to recording in hard disc.
In the case where 2200 clusters from cluster 0 up to cluster 2199 exist on a mini-disc, as shown in FIG. 30, for example, the recording area is partitioned into area (A) from cluster 0 up to cluster 650, area (B) from cluster 651 up to cluster 1100, and area (C) from cluster 1101 up to cluster 2199, thus making it possible to record audio data into, e.g., partitions A and C of respective areas (partitions), and to record data of computer into partition B thereof.
However, in the case where the recording area is partitioned in advance in correspondence with:kind of data in this way, when, e.g., data of computer to be recorded is above capacity of partition B, even if empty areas exist in the partition A and the partition C, data of computer is disadvantageously no longer recorded onto that mini-disc. In contrast, when partition A and partition C are filled with data, even if any empty area exists in the partition B, it is impossible to record audio data beyond that.
Further, management method of dividing the recording area into partitions in this way is management method basically different from the management method having cluster as unit. For example, when a mini-disc having a recording area divided into a plurality of partitions in which data of computer is recorded in a predetermined partition and audio data is recorded in any other partition is reproduced by an apparatus dedicated for reproducing audio data, there is the possibility that the audio data may not be reproduced. Namely, it becomes difficult to guarantee compatibility.
With such circumstances in view, this invention has been made, and makes it possible to record data in a unit of, e.g., sector smaller than a cluster onto a mini-disc in which it is standardized to record data with cluster being a unit.
Further, in accordance with this invention, in the case where an empty area exists, it is possible to record both computer data and audio data at all times as occasion demands.
In addition, this invention makes it possible to ensure compatibility with ordinary mini-disc.